7
7.0
Jul 14, 2015
07/15
Jul 14, 2015
by
William H. Butler; Claudia K. A. Mewes; Chunsheng Liu; Tianyi Xu
7
0
1
We present a rational approach to the design of halfmetallic heterostructures which allows the design of an infinite number of halfmetallic heterostructures. The wide range of materials that can be made halfmetallic using our approach makes it possible to engineer materials with tunable characteristic properties, for example low intrinsic magnetic damping, small magnetic moment or perpendicular anisotropy. We demonstrate the proposed design scheme for a series of transition metal...
( 1 reviews )
Source: http://arxiv.org/abs/1103.3855v1
15
15
Apr 8, 2015
04/15
Apr 8, 2015
by
S. AraujoBetancor; B. T. Gaensicke; K. S. Long; K. Beuermann; D. de Martino; E. M. Sion; P. Szkody
15
0
1
We have obtained HST/STIS data for a total of eleven polars as part of a program aimed to compile a homogeneous database of highquality farultraviolet (FUV) spectra for a large number of cataclysmic variables (CVs). Of the eleven polars, eight were found in a state of low accretion activity (V347Pav, VVPup, V834Cen, BLHyi, MRSer, STLMi, RXJ1554.2+2721 and V895Cen) and three in a state of high activity (CDInd, ANUMa and UWPic). The STIS spectra of the lowstate polars unambiguously reveal the...
( 1 reviews )
Source: http://arxiv.org/abs/astroph/0412180v1
24
24
Apr 8, 2015
04/15
Apr 8, 2015
by
Michael L. Sitko; Lawrence S. Bernstein; Robert J. Glinski
24
0
1
We have reanalyzed the ultraviolet spectrum of HD 44179, the central star(s) of the Red Rectangle nebula, providing improved estimates of the column density, rotational, and vibrational temperatures of the 4th Positive AX system of CO in absorption. The flux shortward of 2200 A is a complex blend of CO features with no discernible stellar photosphere, making the identification of other molecular species difficult, and the direct derivation of the dust extinction curve impossible. We confirm...
( 1 reviews )
Source: http://arxiv.org/abs/0802.2085v1
40
40
Mar 15, 2015
03/15
Mar 15, 2015
by
Mikhail I. Rabinovich; Mehmet K. Muezzinoglu
40
0
1
We present a new paradigm in the study of brain mental dynamics on the basis of the stable transient activity neural networks observed in experiments. This new approach is in contrast to traditional system analysis usually adopted in cognitive modeling. Transient dynamics offers a sound formalism of the observed qualities of brain activity, while providing a rigorous set of analysis tools. Transients have two main features: First, they are resistant to noise, and reliable even in the face of...
( 1 reviews )
Source: http://arxiv.org/abs/0909.1144v1
32
32
Jan 26, 2015
01/15
Jan 26, 2015
by
Arkaitz Zubiaga; Damiano Spina; Enrique Amigó; Julio Gonzalo
32
0
1
This paper explores the realtime summarization of scheduled events such as soccer games from torrential flows of Twitter streams. We propose and evaluate an approach that substantially shrinks the stream of tweets in realtime, and consists of two steps: (i) subevent detection, which determines if something new has occurred, and (ii) tweet selection, which picks a representative tweet to describe each subevent. We compare the summaries generated in three languages for all the soccer games in...
( 1 reviews )
Source: http://arxiv.org/abs/1204.3731v1
100
100
Mar 28, 2014
03/14
Mar 28, 2014
by
J. L. F. Barbon
100
1
1
This is a rendering of a review talk on the state of String Theory, given at the EPS2003 Conference, intended for a wide audience of experimental and theoretical physicists. It emphasizes general ideas rather than technical aspects.
( 1 reviews )
Source: http://arxiv.org/abs/hepth/0404188v1
62
62
Mar 2, 2014
03/14
Mar 2, 2014
by
Roman Sverdlov
62
0
1
The first goal of this paper is to show that discreteness, locality, and relativistic covariance can peacefully coexist if the ordinary spacetime (OST) is replaced with phase spacetime (PST) as a geometric background of a Poisson process, where PST is a spacetime generalization of a notion of phase space (this is a 7dimensional version of the 8dimensional structure proposed by Caianiello). Furthermore, Caianiello's idea of finite acceleration is implemented. After this is done, the paper then...
( 1 reviews )
Source: http://arxiv.org/abs/0910.2498v3
45
45
Nov 7, 2013
11/13
Nov 7, 2013
by
Andrei A. Galiautdinov; David R. Finkelstein
45
0
1
The Dirac equation is not semisimple. We therefore regard it as a contraction of a simpler decontracted theory. The decontracted theory is necessarily purely algebraic and nonlocal. In one simple model the algebra is a Clifford algebra with 6N generators. The quantum imaginary $\hbar i$ is the contraction of a dynamical variable whose backreaction provides the Dirac mass. The simplified Dirac equation is exactly Lorentz invariant but its symmetry group is SO(3,3), a decontraction of the...
( 1 reviews )
Source: http://arxiv.org/abs/hepth/0106273v2
10
10.0



by
J. J. M. in 't Zand; J. Swank; R. H. D. Corbet; C. B. Markwardt
10
0
0
A search for pulsations from the Be Xray binary SAX J2239.3+6116, through observations with the Narrow Field Instruments on BeppoSAX and the Proportional Counter Array on RXTE, yielded the clear presence of a 1247 s coherent oscillation. Given the fairly high Xray luminosity on previous occasions (up to a few times 10^36 erg/s in 2 to 28 keV), the oscillation must be due to the spin of a neutron star. Assuming that the 262 day recurrence time is the orbital period, SAX J2239.3+6116 has both...
Source: http://arxiv.org/abs/astroph/0110695v1
11
11



by
J. E. Prieto; E. Korutcheva; I. Markov
11
0
0
Quantum dots have promising properties for optoelectronic applications. They can be grown free of dislocations in highly mismatched epitaxy in the coherent StranskiKrastanov mode. In this chapter, some thermodynamic aspects related to the wetting in the growth and selfassembly of threedimensional (3D) coherent islands are studied using an energy minimization scheme in a 1+1dimensional atomic model with anharmonic interactions. The conditions for equilibrium between the different phases are...
Source: http://arxiv.org/abs/condmat/0404673v2
We study the semileptonic decays B > Xs e+ e, B > Xs mu+ mu in generic supersymmetric extensions of the Standard Model. SUSY effects are parameterized using the mass insertion approximation formalism and differences with MSSM results are pointed out. Constraints on SUSY contributions coming from other processes (e.g. b > s gamma) are taken into account. Chargino and gluino contributions to photon and Zmediated decays are computed and nonperturbative corrections are considered....
Source: http://arxiv.org/abs/hepph/9907329v1
12
12



by
Albrecht Boettcher; Harold Widom
12
0
0
We present two elementary derivations of the formula for the Toeplitz determinant generated by a pure FisherHartwig singularity.
Source: http://arxiv.org/abs/math/0312198v2
9
9.0



by
Constanze Roedig; Alberto Sesana; Massimo Dotti; Jorge Cuadra; Pau AmaroSeoane; Francesco Haardt
9
0
0
We study the interplay between gas accretion and gravity torques in changing a binary elements and its total angular momentum (L) budget. Especially, we analyse the physical origin of the gravity torques (T_g) and their location within the disc. We analyse 3D SPH simulations of the evolution of initially quasicircular massive black hole binaries (BHBs) residing in the central hollow of massive selfgravitating circumbinary discs. We use different thermodynamics within the cavity and for the...
Source: http://arxiv.org/abs/1202.6063v2
5
5.0



by
Shiro Goto; Satou Kimura; Naoyuki Matsuoka; Tran Thi Phuong
5
0
0
Quasisocle ideals, that is the ideals $I$ of the form $I= Q : \mathfrak{m}^q$ in a Noetherian local ring $(A, \mathfrak{m})$ with the Gorenstein tangent cone $\mathrm{G}(\mathfrak{m}) = \bigoplus_{n \geq 0}{\mathfrak{m}}^n/{\mathfrak{m}}^{n+1}$ are explored, where $q \geq 1$ is an integer and $Q$ is a parameter ideal of $A$ generated by monomials of a system $x_1, x_2, ..., x_d$ of elements in $A$ such that $(x_1, x_2, ..., x_d)$ is a reduction of $\mathfrak{m}$. The questions of when $I$ is...
Source: http://arxiv.org/abs/0710.1387v2
7
7.0



by
P. Balbi; A. Giovannini
7
0
0
Following HERA experiments our interest is focused, in the present paper, on charmonium production in leptonproton collisions. Inelastic J/\psi electroproduction is quite difficult to be measured due to the low rates of events; almost all experimental studies are indeed performed in photoproduction regime. J/\psi resonance is considered as the product of the hadronization of a c \bar{c} pair generated via bosongluon fusion. The leading order contribution to the differential cross section,...
Source: http://arxiv.org/abs/hepph/0212168v1
10
10.0



by
Gleb Arutyunov; Emery Sokatchev
10
0
0
We discuss the perturbative behavior of the 1/2 BPS operators in N=2 SCFT on the example of two very similar quadrilinear composite operators made out of hypermultiplets. An explicit oneloop computation shows that one of them is protected while the other acquires an anomalous dimension. Although both operators are superconformal primaries in the free case, the quantum corrections make the latter become a 1/2 BPS descendant of the Konishi multiplet, while the former remains primary. The...
Source: http://arxiv.org/abs/hepth/0209103v1
5
5.0



by
Decio Levi; Christian Scimiterna
5
0
0
We show that one can define through the symmetry approach a procedure to check the linearizability of a difference equation via a point or a discrete ColeHopf transformation. If the equation is linearizable the symmetry provides the linearizing transformation. At the end we present few examples of applications for equations defined on four lattice points.
Source: http://arxiv.org/abs/1302.0154v1
11
11



by
Raul Jimenez; Benjamin Panter; Alan Heavens; Licia Verde
11
0
0
Using the spectroscopic sample of the SDSS DR1 we measure how gas was transformed into stars as a function of time and stellar mass: the baryonic conversion tree (BCT). There is a clear correlation between early star formation activity and presentday stellar mass: the more massive galaxies have formed about 80% of their stars at $z>1$, while for the less massive ones the value is only about 20%. By comparing the BCT to the dark matter merger tree, we find indications that star formation...
Source: http://arxiv.org/abs/astroph/0403294v2
9
9.0



by
Benjamin K. Tippett; Kayll Lake
9
0
0
Exploiting the existence of two "cosmological" constants, one associated with the classical Lovelock theorem and one with the vacuum energy density, we argue, in a model independent way, that in spatially closed FLRW cosmologies with a positive definite effective cosmological constant there exists a range in this constant that serves as a sufficient condition for the satisfaction of the null, weak, strong and dominant energy conditions at a bounce. The application of energy conditions...
Source: http://arxiv.org/abs/grqc/0409088v1
10
10.0



by
R. G. Sharp; R. G. McMahon; M. J. Irwin; S. T. Hodgkin
10
0
0
We report the first results of an observational program designed to determine the luminosity density of high redshift quasars (z > 5 quasars) using deep multicolour CCD data. We report the discovery and spectra of 3 i < 21.5 high redshift (z > 4.4) quasars, including one with z > 5. At z=5.17, this is the fourth highest redshift quasar currently published. Using these preliminary results we derive an estimate of the M \rm_B <  25.0 (M \rm_{AB1450} <  24.5) quasar space...
Source: http://arxiv.org/abs/astroph/0103079v2
11
11



by
Masato JIMBO; Hidekazu TANAKA; Toshiaki KANEKO; Tadashi KON; MINAMITATEYA collaboration
11
0
0
We introduce a new method to treat Majorana fermions on the GRACE system which has been developed for the computation of the matrix elements for the processes of the standard model. In the standard model, we already have such particles as Dirac fermions, gauge bosons and scalar bosons in the system. On the other hand, in the SUSY models there are Majorana fermions. In the first instance, we have constructed a system for the automatic computation of crosssections for the processes of the SUSY...
Source: http://arxiv.org/abs/hepph/9503363v1
14
14



by
Ludovic Berthier
14
0
0
The rheological behavior of soft glassy materials basically results from the interplay between shearing forces and an intrinsic slow dynamics. This competition can be described by a microscopic theory, which can be viewed as a nonequilibrium schematic modecoupling theory. This statistical mechanics approach to rheology results in a series of detailed theoretical predictions, some of which still awaiting for their experimental verification. We present new, preliminary, results about the...
Source: http://arxiv.org/abs/condmat/0209394v1
8
8.0



by
A. Retter; E. M. Leibowitz
8
0
0
It was believed, with little theoretical basis, that the accretion disk (AD) is destroyed in nova outbursts, and recovers only a few decades later. In my thesis I tried to find observational signature for the presence of ADs in young novae. I will discuss two cases: 1. Nova V1974 Cyg 1992  we found permanent superhumps about 2.5 years after the nova eruption. This is a very strong evidence for the presence of the AD according to the disk  instability model. 2. Nova V1425 Aql 1995 ...
Source: http://arxiv.org/abs/astroph/9708194v1
11
11



by
J. GomezGardenes; B. A. Malomed; L. M. Floria; A. R. Bishop
11
0
0
We consider a lattice equation (Salerno model) combining onsite selffocusing and intersite selfdefocusing cubic terms, which may describe a BoseEinstein condensate of dipolar atoms trapped in a strong periodic potential. In the continuum approximation, the model gives rise to solitons in a finite band of frequencies, with sechlike solitons near one edge, and an exact peakon solution at the other. A similar family of solitons is found in the discrete system, including a peakon; beyond the...
Source: http://arxiv.org/abs/nlin/0603050v1
5
5.0



by
J. Bolz; R. Jakob; P. Kroll; N. G. Stefanis
5
0
0
We point out some serious problems in the investigation of Kundu et al. which claims agreement with the existing data of the proton form factor, calculated without taking into account the intrinsic k_{perp}dependence of the proton wave function.
Source: http://arxiv.org/abs/hepph/9807328v1
9
9.0



by
P. Papakonstantinou; R. Roth; N. Paar
9
0
0
We examine to which extent correlated realistic nucleonnucleon interactions, derived within the Unitary Correlation Operator Method (UCOM), can describe nuclear collective motion in the framework of firstorder randomphase approximation (RPA). To this end we employ the correlated Argonne V18 interaction in calculations within the socalled "Extended" RPA (ERPA) and investigate the response of closedshell nuclei. The ERPA is a renormalized RPA version which considers explicitly the...
Source: http://arxiv.org/abs/nuclth/0609039v1
7
7.0



by
G. Kofinas; E. Papantonopoulos; V. Zamarias
7
0
0
An analysis of a spherically symmetric braneworld configuration is performed when the intrinsic curvature scalar is included in the bulk action. In the case when the electric part of the Weyl tensor is zero, all the exterior solutions are found; one of them is of the Schwarzschild(A)dS(4) form, which is matched to a modified OppenheimerVolkoff interior solution. In the case when the electric part of the Weyl tensor is non zero, the exterior Schwarzschild(A)dS(4) black hole solution is...
Source: http://arxiv.org/abs/hepth/0210006v1
Recently the multitude of vacua in string theory have led some authors to advocate the anthropic principle as a possible resolution for the contrived set of parameters that seem to govern our universe. I suggest that string theories should be viewed as effective theories, and hence of limited utility rather than as ``theories of everything''. I propose that quantum gravity should admit a form of determinism and that the selfdual points under phasespace duality should play a prominent role in...
Source: http://arxiv.org/abs/hepth/0312167v3
11
11



by
D. Cavalcanti; L. Aolita; A. Ferraro; A. GarciaSaez; A. Acin
11
0
0
We address the presence of bound entanglement in stronglyinteracting spin systems at thermal equilibrium. In particular, we consider thermal graph states composed of an arbitrary number of particles. We show that for a certain range of temperatures no entanglement can be extracted by means of local operations and classical communication, even though the system is still entangled. This is found by harnessing the independence of the entanglement in some bipartitions of such states with the...
Source: http://arxiv.org/abs/0909.5609v1
7
7.0



by
B. W. Jiang; Ke Zhang; Aigen Li
7
0
0
The mysterious 21mu emission feature seen in 12 protoplanetary nebulae (PPNe) remains unidentified since its first detection in 1989. Over a dozen of candidate materials have been proposed within the past decade, but none of them has received general acceptance. Very recently, silicon carbide (SiC) grains with impurities were suggested to be the carrier of this enigmatic feature, based on recent laboratory data that doped SiC grains exhibit a resonance at \~21mu. This proposal gains strength...
Source: http://arxiv.org/abs/astroph/0507626v1
11
11



by
Gil Refael; Jinseong Heo; Marc Bockrath
11
0
0
In this paper we study electron interference in nanotube loops. The conductance as a function of the applied voltage is shown to oscillate due to interference between electron beams traversing the loop in two opposite directions, with slightly different velocities. The period of these oscillations with respect to the gate voltage, as well as the temperatures required for the effect to appear, are shown to be much larger than those of the related FabryPerot interference. This effect is...
Source: http://arxiv.org/abs/condmat/0608365v1
Let $S(d,N)$ denote the number of permutations in the symmetric group on $[N]$ which have no decreasing subsequence of length $d+1.$ We prove that $S(d,dn)$ is asymptotically equal to the number of standard Young tableaux of rectangular shape $R(d,2n)$ in the limit $n \to \infty,$ with $d$ fixed.
Source: http://arxiv.org/abs/0906.5167v2
9
9.0



by
Stanislaw Mrowczynski; Anton Rebhan; Michael Strickland
9
0
0
We generalize the hardthermalloop effective action of the equilibrium quarkgluon plasma to a nonequilibrium system which is spacetime homogeneous but for which the parton momentum distribution is anisotropic. We show that the manifestly gaugeinvariant BraatenPisarski form of the effective action can be straightforwardly generalized and we verify that it then generates all npoint functions following from collisionless gaugecovariant transport theory for a homogeneous anisotropic plasma....
Source: http://arxiv.org/abs/hepph/0403256v3
This general talk is geared toward nonspecialists and addresses three questions: (1) What types of cosmological simulations are done? (2) What are the relevant problems to address and what results can one expect? (3) How can one tell if the results are reasonable?
Source: http://arxiv.org/abs/astroph/9509082v1
12
12



by
N. Masetti; E. Palazzi; L. Bassani; A. Malizia; J. B. Stephen
12
0
0
The results of an optical spectroscopy campaign performed at the Astronomical Observatory of Bologna in Loiano (Italy) on three hard Xray sources detected by INTEGRAL (IGR J173030601, IGR J180271455 and IGR J21247+5058) are presented. These data have allowed a determination of the nature for two of them, with IGR J173030601 being a low mass Xray binary in the Galaxy and IGR J180271455 a background Type 1 Seyfert galaxy at redshift z = 0.035. IGR J21247+5058, instead, has a quite puzzling...
Source: http://arxiv.org/abs/astroph/0409250v1
11
11



by
A. M. Bernstein; E. Shuster; R. Beck; M. Fuchs; B. Krusche; H. Merkel; H. Stroher
11
0
0
A rigorous multipole analysis of the recent {\gamma}p > \pi^{0}p cross section measurement is presented. The data were taken using the photon spectrometer TAPS at the tagged photon beam of the Mainz microtron. The s and p wave multipoles were extracted using minimal model assumptions. The predicted unitary cusp for the s wave multipole E_{0+} due to the two step {\gamma}p > \pi^{+}n > \pi^{0}p reaction was observed. The results are consistent with one loop chiral perturbation theory...
Source: http://arxiv.org/abs/nuclex/9610005v1
In this paper we develop a formalism which models all massive particles as travelling at the speed of light(c). This is done by completing the 3velocity v of a test particle to the speed of light by adding an auxiliary 3velocity component z for the particle. According to the observations and laws of physics defined in our spacetime these vectors are generalized to domains and then two methods are developed to define c domain in terms of our spacetime(v domain). By using these methods the...
Source: http://arxiv.org/abs/grqc/0210068v2
5
5.0



by
Ken Dykema; Florin Radulescu
5
0
0
We introduce notation Q(1) * ... * Q(n) * L(F_r)$ for von Neumann algebra II_1 factors where $r$ is allowed to be negative. This notation is defined by rescalings of free products of II_1 factors, and is proved to be consistent with known results and natural operations. We also give two statements which we prove are equivalent to isomorphism of free group factors.
Source: http://arxiv.org/abs/math/0105114v1
17
17



by
S. Alam; S. Haider; Aurangzeb
17
0
0
The principles and detection of gravitational waves by resonant antennas are briefly discussed. But the main purpose of this short note is to compare the two geometries of resonant antennas, the wellknown cylindrical to the spherical type. Some features of a two sphere observatory are also discussed.
Source: http://arxiv.org/abs/grqc/9702016v1
Recent numerical MHD simulations suggest that magnetic activity may occur in latetype giants. A entire red supergiant with stellar parameters equal to Betelgeuse was modelled in 3d with the highorder "Pencil Code". Linear kinematic and nonlinear saturated dynamo action are found and the nonlinear magnetic field saturates at a superequipartition value, while in the linear regime two different modes of dynamo action are found. Magnetic activity of latetype giants, if it exists,...
Source: http://arxiv.org/abs/astroph/0409192v1
13
13



by
George Georgiou; Valentin V. Khoze
13
0
0
It was proposed in hepth/0403047 that all tree amplitudes in pure YangMills theory can be constructed from known MHV amplitudes. We apply this approach for calculating tree amplitudes of gauge fields and fermions and find agreement with known results.The formalism amounts to an effective scalar perturbation theory which offers a much simpler alternative to the usual Feynman diagrams in gauge theory and can be used for deriving new simple expressions for tree amplitudes. At tree level the...
Source: http://arxiv.org/abs/hepth/0404072v3
9
9.0



by
Naoki Masuda; Hiroyoshi Miwa; Norio Konno
9
0
0
Many real networks are equipped with short diameters, high clustering, and powerlaw degree distributions. With preferential attachment and network growth, the model by Barabasi and Albert simultaneously reproduces these properties, and geographical versions of growing networks have also been analyzed. However, nongrowing networks with intrinsic vertex weights often explain these features more plausibly, since not all networks are really growing. We propose a geographical nongrowing network...
Source: http://arxiv.org/abs/condmat/0409378v2
9
9.0



by
Amit Verma; Anirban Pathak
9
0
0
Recently we have shown that the reduction of the CarruthersNieto symmetric quantum phase fluctuation parameter (U) with respect to its coherent state value corresponds to an antibunched state, but the converse is not true. Consequently reduction of U is a stronger criterion of nonclassicality than the lowest order antibunching. Here we have studied the possibilities of reduction of $U$ in intermediate states by using the Barnett Pegg formalism. We have shown that the reduction of phase...
Source: http://arxiv.org/abs/0801.0717v1
8
8.0



by
D. J. Pisano; David G. Barnes; Brad K. Gibson; Lister StaveleySmith; Ken C. Freeman; .
8
0
0
We present results from our Parkes Multibeam HI survey of 3 loose groups of galaxies that are analogous to the Local Group. This is a survey of groups containing only spiral galaxies with mean separations of a few hundred kpc, and total areas of approximately 1 sq. Mpc; groups similar to our own Local Group. We present a census of the HIrich objects in these groups down to an M(HI), 1sigma sensitivity ~7x10^5 M(sun), as well as the detailed properties of these detections from followup...
Source: http://arxiv.org/abs/astroph/0310094v1
I obtain the inverse of the correlation length exponent at the superfluidBose glass quantum critical point as a series in small parameter $\sqrt{d1}$, with d being the dimensionality of the system, and compute the first two terms using a novel fieldtheoretic technique. For d=2 I find $\nu_s = 0.81$ and $\nu_c = 1.03$, for shortrange and Coulomb interactions between bosons, respectively. When combined with the exact values of the dynamical critical exponents $z_s = d$ and $z_c = 1$, these...
Source: http://arxiv.org/abs/condmat/0001040v2
11
11



by
Charles C. Dyer; Chris Oliwa
11
0
0
Contrary to a claim, the Schwarzschild solution insertion in an expanding universe model, the so called "Swiss cheese" model, does not possess an extrinsic curvature discontinuity. We show that both the intrinsic metric and the extrinsic curvature are continuous, and point out the error that led to the claim.
Source: http://arxiv.org/abs/astroph/0004090v1
13
13



by
Diana Iuşan; Kunihiko Yamauchi; Paolo Barone; Biplab Sanyal; Olle Eriksson; Gianni Profeta; Silvia Picozzi
13
0
0
Aiming at increasing the ferroelectric polarization in AFME ortho\hmo, we investigate the inplane strain effects on both the magnetic configuration and the polarization by means of density functional theory calculations and model Hamiltonian approaches. Our results show that the net polarization is largely enhanced under compressive strain, due to an increase of the electronic contribution to the polarization, whereas the ionic contribution is found to decrease. We identify the...
Source: http://arxiv.org/abs/1102.2168v1
Recent advances in electron and positron sources have resulted in new capabilities driven in most cases by the increasing demands of advanced accelerating systems. Electron sources for brighter beams and for high averagecurrent beams are described. The status and remaining challenges for polarized electron beams are also discussed. For positron sources, recent activity in the development of polarized positron beams for future colliders is reviewed. Finally, a new proposal for combining laser...
Source: http://arxiv.org/abs/physics/0008018v1
5
5.0



by
Denis Kast; Lars Kecke; Joachim Ankerhold
5
0
0
The trend to fabricate electrical circuits on nanoscale dimensions has led to impressive progress in the field of molecular electronics in the last decade. A theoretical description of molecular contacts as the building blocks of future devices is challenging though as it has to combine properties of Fermi liquids in the leads with charge and phonon degrees of freedom on the molecule. Apart from ab initio schemes for specific setups, generic models reveal characteristics of transport...
Source: http://arxiv.org/abs/1104.4903v3
14
14



by
C. Aubin; C. Bernard; C. DeTar; M. Di Pierro; E. D. Freeland; Steven Gottlieb; U. M. Heller; J. E. Hetrick; A. X. ElKhadra; A. S. Kronfeld; L. Levkova; P. B. Mackenzie; D. Menscher; F. Maresca; M. Nobes; M. Okamoto; D. Renner; J. Simone; R. Sugar; D. Toussaint; H. D. Trottier
14
0
0
We present the first lattice QCD calculation with realistic sea quark content of the D^+ meson decay constant f_{D^+}. We use the MILC Collaboration's publicly available ensembles of lattice gauge fields, which have a quark sea with two flavors (up and down) much lighter than a third (strange). We obtain f_{D^+} = 201 +/ 3 +/ 17 MeV, where the errors are statistical and a combination of systematic errors. We also obtain f_{D_s} = 249 +/ 3 +/ 16 MeV for the D_s meson.
Source: http://arxiv.org/abs/heplat/0506030v2